Manage Picky and Fussy Eaters

First of all it is important to define picky/fussy eating and try to categorize it as a disorder or (without dismissing it) just a deviant behaviour in infancy or childhood .

And if it is a disease /disorder how can we prevent and treat it- namely eventual consequences of undernutrition or ponctual nutritional deficits ?

But if it is a behaviour problem ,how serious and deviant from normal can it be , and how can we tackle it , not being to much medical oriented ?

And, most of all, is it a front runner of more pervasive behaviour problems , that are going to reveal themselves later ?

Finally in both circunstances can we help the parents or caregivers to cope with a situation that transforms meals in a battlefield or in ritualistic sessions ?